A: No. Unlike some old MTK phones, RDA chips have no on-phone repair code. You must use a PC.

A: On the keypad, try *#8378# or *#*#8378#*#*. If that works, you can navigate to "Telephony" and see IMEI info, but you cannot repair it from there.

If you are looking for a simple dialer code like *#06# (which just displays the IMEI) or a generic engineering code to rewrite a Coolsand CPU, you might be disappointed.

Unlike older MTK (MediaTek) devices which had widely known engineering modes (like *#*#3646633#*#* or mobile uncle tools), Coolsand/RDA CPUs are much more closed off.

While you might find codes online like *#364663# or *#87# to enter Engineering Mode, these menus rarely allow you to rewrite an IMEI number. They usually allow you to view hardware versions or perform audio tests, but not modify the NV data (where the IMEI is stored).

The IMEI (International Mobile Equipment Identity) is a 15-digit unique identifier. On RDA chipsets, corruption typically occurs due to:

When the IMEI is corrupted, the phone shows "Invalid IMEI," "Null IMEI," or "IMEI=0." The result is no cellular network registration, no calls, and no mobile data.

If the GUI buttons fail, use the Terminal inside CoolSand RDA: